Oven and the like with heat circulating means therefor



May T. LYDON V OVEN AND THE LIKE WITH HEAT CIRCULATING MEANS THEREFORFiled April 16, 1951 5 Sheets-Sheet 1 IN VEN TOR.

y 1936- 'r. LYDON 9 29 OVEN AND THE LIKE WITH HEAT QIRCULATING MEANSTHEREFOR Filed April 16, 1931 3 Sheets-Sheet 2 May 5, '1936. T. LYDON2,039,429

OVEN AND THE LIKE WITH HEAT CIRCULATING MEANS THEREFOR Fi-l-ed- Ap-ril1a, .1951 $Sheets-Sheet s IN VEN TO.

Patented May 5, 1936 OVEN AND THE LIKE WITH HEAT CIRCU- LATING MEANSTHEREFOR Timothy Lydon, New York, N. Y.

Application April 16, 1931, Serial No. 530,592

6 Claims.

This invention relates to improvements in ovens for drying, dehydration,polymerization, vulcanizing, heat treating and glass annealing and itconsists in the novel features, which are 5 hereinafter described. Thisapplication is in part a continuation of my prior co-pending applicationfiled Dec. 6, 1929 under Serial Number 412,168.

An object of the present invention is to provide a perfected process andan oven, in which the atmosphere is maintained at a high degree ofuniformity of temperature throughout the oven.

Another object of my invention is to provide a perfected oven, in which,by a continuous and rapid circulation of air, the formation of gaspockets and the accumulation of inflammable vapors produced by drying orby chemical reaction, is prevented and the resulting explosions avoided.

A further object of my invention is to maintain the heating means, orparts radiating heat in the oven at uniform and relatively lowtemperature.

A further object of my invention is to maintain an internal aircirculation and agitation in the oven with the oven atmosphere beingmaintained at relatively low pressures therein.

A further object of my invention is to provide an exhaust outlet anddamper for controlling same, for discharging a part of the aircirculated through the oven, which air is mixed with the vapors givenolf by sundry articles during the process of baking within the oven.

A further object is to constantly control and dilute the vaporaccumulation within the oven,

and to this end means are provided for discharging a part of the vaporsand replacing the same with induced fresh air from outside the oven, toobviate inflammable or explosive mixtures within the oven and to providefresh air for supply of oxygen for the process. I.

Another object of the present invention is 1, to increase the efficiencyand sensitivity of the temperature controlling instrument by utilizing astream flow to sweep away the quiescent film of air which surrounds andtends to prevent heat Fig. 1' is a longitudinal vertical section of oneview to obtaining uniform conditioning atmosphere within same.

A further object of the present invention is to provide a centrifugalblower on the inside of the oven, thereby permitting wider and shorter 5air ducts to be used without the necessity of bringing same outside theoven with consequent loss of heat from same and to prevent thedeposition or condensation by cooling of inflammable or harmfulcarbonaceous material in the ducts and blower.

Another object of my invention is to increase the efficiency of theapparatus as a whole by reducing theconsumption of power used inrecirculating the air and by increasing the emciency 15 of the radiatingsurfaces producing heat within the oven.

Finally, as will hereinafter be ascertained, an object of this inventionis to'provide an oven of economical construction and low cost to operateefficiently and with low power or fuel consumption and provided with arapid circulating system and means for simultaneously exhausting a partof the vapor laden air within the oven and replacing same with aninduced draft of fresh air which is immediately diffused.

Various further objects and advantages of the present invention willhereinafter appear.

I attain these objects by the oven and the appurtenances thereof,several forms of which are shown in the drawings or by mechanicalequivalents or modifications of same.

,In the drawings:'

form of my oven on the line i| of Fig. 4, looking in the direction ofthe arrows and showing sundry parts in elevation.

Rig. 2 is a transverse vertical section on the line 2-2 of Fig. 4,showing sundry parts in elevation;

Fig. 3 is a horizontalsectional top view on the line 3-3 of Fig. 1 withapart of the casing 22 cut away to show sundry parts in plan view.

Fig. 4 is a plan view of the oven, with the top of the fresh air flueremoved to show sundry parts 45 in plan. w v

Fig. 5 is a plan view in detail of the fresh air inlet damper plates.

Fig. 6 is across sectional detail of the fresh 5 air inlet damperplates.

Fig. 7 is a diagrammatic outline in longitudinal vertical section of anelectrically heated truck type oven with recirculation in a verticaldirection.

Fig. 81s a diagrammatic outline in longitudinal 55 dinal verticalsection of an indirect gas heated conveyor type oven provided withrecirculation.

Fig. 13 is a diagrammatic outline in longitudinal vertical section of anindirect gas heated cabinet type oven with vertical recirculation.

Fig. 14 is a diagrammatic outline in longitudinal vertical section of anindirect gas heated cabinet type oven with shelves, and provided withhorizontal circulation between the shelves.

Fig. 15 is a diagrammatic outline in longitudinal vertical section of anindirect gas heated two compartment cabinet type oven with shelves,provided with circulation across the shelves.

Fig. 16 is a diagrammatic outline in longitudinal vertical section of anelectrically heated cabinet type oven with shelves, and provided withcirculation in a vertical direction through the shelves.

Fig. 1'7 is a diagrammatic outline in longitudinal vertical section ofan electrically heated cabinet type oven with shelves and circulationhorizontally between the shelves.

Like characters of reference refer to like parts throughout the severalviews:

II designates an outer metal casing, I2 an inner metal casing and I3heat insulating material of the walls of the outer shell I4 of anindirect gas heated oven, shown in Figs. 1, 2, 3 and 4. The doors I5 ofthe oven consist of similar parts.

A centrifugal fan or blower I5 is overhung interiorly of said shell I4under the top I! thereof, to revolve in a horizontal plane, and issecured to a vertical shaft I8, supported in suitable bearings I9 and20; said shaft I8 has secured thereto at the upper end thereof asuitable source of power 2 I, which may be either a belt driven pulleyor a direct connected motor.

The fan I6 is enclosed between the top I! of the oven and a metal shell22 supported immediately below it. The shell 22 extends across the depthof the oven to be connected to and supported by the combustion chambers24a and 21a which in turn are connected to the inner metal casing I2 bythe angle irons 23; space is allowed between the combustion chamber 24aand 21a and the inner metal casing I2 to form the pressure ducts 24 and21 and these form a continuation of the duct 28 formed between the metalshell 22 and the inner metal casing I2. Dis- Fig. 12 is a diagrammaticoutline in longitubustion of a suitable fuel gas, these burners aredisposed immediately above perforated plates 56 which allow the passageof secondary air therethrough from the secondary air intake ducts 53;

for the complete combustion of the fuel gas being .side, and before theyescape to the outside,

through the stack 52.

InFig. 2 the openings 49 as indicated are for the accommodation of atruck or carriage 33 provided with shelves 34 both shown dotted, and forsupporting the material to be treated. The doors I 5 of the oven shellI4 are employed to admit the said truck or carriage into the oven andits withdrawal therefrom.

During a baking process within my oven vapors or fumes may be formed andit is desirable to positively ventilate the oven at all times. To thisend the fan I6 is provided in addition to its main blades IBa withsubsidiary blades I6b on its upper surface and is disposed concentricwith and immediately under the fresh air inlet 38 and its damper plates3i and 40.

To efiect and regulate the discharge from the oven of vapors or fumesresulting from the baking process within the oven, an outlet 35extending through the outer shell I4 of the oven from the duct 28 and adamper 36 hingedly supported at 31 and a damper regulating rod 3| areprovided as shown in Figs. 1 and 3.

A fresh air flue 48 leading to the fresh air intake 38 is built aroundthe outlets 35 and 52 so that some of the heat escaping through theseoutlets may be used to preheat the incoming air.

During a baking process in an oven of the type indicated in Figs. 1, 2,3 and 4, the inlet damper plate 39 which is pivoted around a projection4I on the fixed damper plate 40 is moved by means of the regulating rod3I so that the holes 42 always register wholly or in part with the holes43 in the fixed plate 40. The outlet damper 36 is also likewise neverentirely closed but opened to the extent found by the operator to suithis particular needs best. The stops 44 and 45 are so placed on theregulating rod 3I of the intake damper that this plate can never bemoved beyond certain limits, these limits being such that the holes 42and 43 in the damper plates always register to some extent.

When an oven of the type described is in operation a stream of fresh airis being drawn in by the subsidiary blades IIib on the fan I6 and astream of vapor laden air is being discharged through the outlet 35simultaneously with a rapidly circulated stream of heated air beingforced through and across the material placed within the oven and in thedirections indicated by arrows in Fig. 2. The fresh air induced into thepassage 38 is heated during its passage along the heated sides of thecombustion chambers 24a and 21a and serves to reduce the temperature ofthese surfaces.

In a form of my oven above described the operator is afforded means foreffecting a high degree of uniformity in temperature, and positivecontrol over ventilation within the oven, such as is adaptable to a widevariety of useful applications.

In the forms of my oven hereafter described the same rapid circulationof air with the accompanying processes already described, are broughtabout in modified forms to suit the nature of the work to be handledwithrespect to size, shape, time of baking, amount to be handled, methodof handling and such other considerations as enter into factoryproduction.

Fig. 7 shows a modification of my oven adapted for electric heating andtruck loading. Aninterior sheet metal shell 51 forms the inside wall ofthe pressure ducts 24 and 21.

The electric heating units 58 and 59 placed close to the perforations 60and vanes Si in the lower portion of the shell 51, heat the air directedagainst them by said vanes and perforations, and the baflle 62 placednear the intake to the fan l6 helps to spread out the course taken bythe air through the oven.

In Fig. 8 I indicate how my oven may be adapted for direct oil or gasheating. In this modification the products of combustion are allowed toenter the oven proper and are used for heating. The oil burner 63 placedin a suitable refractory firebox 64 generates heat and hot gasses. Thegases and convection currents arising from the combustion are assistedin their vertical rise by draft induced on them by the air passing overthe vane 65 disposed as indicated above the outlet 66 to the firebox 64.

Another method of heating an oven of this type is indicated on the rightside of Fig. 8 in which a gas burner 4'! provided with a secondary airsupply duct 53 and disposed under a vane 61 which dissipates some of theheat generated by the flame 41b of the burner 41 and induces a draft tocarry away the hot products of combustion, in a direction indicated bythe arrows. The fresh air intake for this type of oven may be locatednear the floor.

Fig. 9 shows a modification of my oven direct gas heated to take twotrucks and with circulation from each side across the trucks to acentral passage H between the trucks. The sheet metal shell 57!providedwith perforations 68 matching the spaces between the shelves 34of the trucks 33, forms the pressure ducts 24 and 21 which are closed,in this modification, at the bottom. The hot gases of combustion risingfrom the burners 41 are taken in circulation by the cross currents ofair between the shelves and together are drawn out from the passage iito the fan l6.

Fig. 10 indicates a two truck electrically heated oven adapted forhorizontal and vertical air circulation. In this modification thepressure ducts 24 and 2?, are partly restricted at their lower ends bynecks l4 and i5 so that part of the air is forced across the material inthe oven and the remainder is blown across the heaters to mix and risewith fresh air drawn through the fresh air inlets lb and ll disposedbelow the electric heaters 8|.

Fig. 11 shows a two compartment modification of my oven provided withmeans for cross circulation and electric heating. This oven may beadapted for truck, drawer or shelf loading. The space '38 between thecompartments I9 and 88 contains the electric .heating elements 8| andforms the suction duct towards which circulation takes place from thepressure ducts 24 and 21.-

In Fig. 12 I show a modification of my oven adapted for indirect gasheating and with a conveyor for continuous operation. The material to bebaked is placed on the conveyor 82 which is slowly drawn through theoven by-the sprockets 83 and a suitable driving mechanism not shown.

Gas is burned in the burners 41 which are supplied with secondary airthrough the ducts 53. The combustion chambers 24b and 21b carry away theproducts of combustion to the outlets 84 and 85. The fan I6 which isdirect driven by the motor 88 is disposed so that its secondary bladesl6b .draw a stream of fresh air as indicated by the arrows through thepassages 81 and along the hot surfaces of the combustion chambers 24band 21b. The fan I6 blows the incoming preheated fresh air across theupper hot surfaces 89 and 90 through the perforated floor ill] of theoven and the material on the perforated conveyor 82 as indicated by thearrows, and is drawn down through the material and back into the .fanabove the funnel 9|. A certain part of the air is exhausted at each openend of the oven and the hoods 92 and 93 are provided to carry away thesevapors. In an oven of this nature room for circulation of air betweenthe articles to be baked must be allowed when they are placed on theconveyor at the loading end.

I indicate in Fig. 13 an indirect gas heated cabinet type oven with aircirculation in a vertical direction. The fan I6 is direct connected tothe motor 88 and blows fresh air and recirculated air over the hotsurfaces of the combustion chambers 24b and 21b. The air is forcedupward through the pressure ducts 24 and 21 and down through theinterior space 94 of the oven. The products of combustion are carriedaway by the outlets 95 and 96.

I indicate in Fig. 14 an indirect gas heated cabinet type oven withshelves and cross circulation between the shelves. In this modificationthe fresh air is induced through an opening 91 in the suction passage98, by the passage over a vane 91a of the recirculated air. The combinedfresh and recirculated air is then blown over the hot surface of thecombustion chamber 241) while a part thereof is exhausted through thestack Hll containing the damper E02. The air passes across the oven fromthe pressure duct I80 to the suction duct 98.

In Fig. 15 I show an indirect gas heated two compartment cabinet typeoven with shelves and cross circulation between the shelves. The oven isdivided into two compartments I03 and I84 and a central suction passage99. By dividing the oven as here indicated and narrowing the width ofthe trays or shelves to fit therein, and lessening the. horizontaldistance through which the air is circulated it is possible to obtainthe very great degree of temperature uniformity desired in bakingprocesses involving the fractional distillation of volatiles fromsemi-solid materials.

In Fig. 16 I indicate an electrically heated cabinet type oven furnishedwith perforated shelves and adapted for vertical recirculation throughthe material placed on said shelves. No fresh air inlet is provided inthis modification which is one used for baking or heating processeswhich require uniform temperature and exact temperature control but inwhich the processes brought about by heating, do not result in theformation of vapors or fumes to any marked extent. The electric heatingunits 81 are placed in the pressure ductsformed by the side walls of theoven and the interior shell 51.

I indicate in Fig. 17 an electrically heated cabinet type oven withshelves and trays I01 and a f esh air intake 91 located in the suctionduct 98. The electric heater 8| is placed directly in front of the fanIt so that it is keptat a low temperature by the stream of air which isblown over it.

The heated air passes between the trays ID! in traveling from one sideof the oven to the other and in so doing bakes the material .therein toa uniform degree and immediately carries away all vapors as soon as theyare formed.

Many other changes may be made in the modifications of my oven withoutdeparting from the main scope of my invention, and parts of my inventionmay be used without other parts.

I do not therefore restrict myself to the details as shown in thedrawings, but I intend to include also all mechanical equivalents andobvious modifications of the same within the scope of my invention.

I claim as my invention:

1. In combination, a shell having opposite side walls and asubstantially horizontal bottom wall; an approximately horizontal thinheat conducting intermediate wall slanting upwardly from near themid-part 'of said bottom wall to said opposite walls to form a heatingchamber; heating burners in said heating chamber; ducts supplyingcombustion air to the lower part of said chamber; outlet means at theupper outer part of the chamber; a centrifugal fan in the interior ofsaid shell near, and substantially axially perpendicular to said bottomwall, above the mid-part of the-intermediate wall and adapted to throwair from the vanes against said intermediate wall; a partition extendingabove said fan having an intake opening at the axis of the motor; saidslanting floor providing an unobstructed guide means for air from thetips of the fan blades to the respective flues; whereby air is evenlydistributed substantially tangentially from said tips, free of eddiesand free of lateral gravity components, whereby even distribution ismaintained.

2. An oven comprising a substantially rectangular shell of heatinsulating material forming a material receiving space and having asubstantially horizontal wall having a ventilating opening through a midpart thereof; an axially vertical fan shaft passing vertically axiallythrough said opening and spaced from contact with the shell; acentrifugal rotor fast on the shaft within the shell, near saidhorizontal wall, and comprising an upper ventilating fan and a lowercirculating fan, each fan having blades extending outwardly from saidshaft, whereby air drawn directly from said opening and from said spaceinto the fans at the middle part, is centrifugally forced outwardly andmixed and evenly distributed substantially throughout said space,whereby even distribution is maintained; said intermediate wall havingan outlet opening near said ventilating opening; and heating means inthe shell disposed to heat upwardly moving currents of air only, therebyaiding convection and circulation.

3. In combination, a shell having opposite side walls and asubstantially horizontal intermediate top wall; a centrifugal fan in theinterior of said shell near, substantially adjacent to and axiallyperpendicular to said intermediate wall; pressure flues on oppositesides of said interior near said opposite walls and extendingsubstantially from top to bottom and front to rear thereof and forming adeep vertical material receiving space therebetween; a pair of verticalsets of horizontal shelves in said space leaving a vertical passagebetween the sets vertically under the axis of the fan; said flues havingaseries of openings directed directly between adjacent shelves of thesame set; said flues being provided with passage openings at the upperend parts and closed at the lower end; and a partition extending acrosssaid interior near said fan between the fan and said space and.cooperating with said intermediate wall to form a fan casing having aninlet from said interior at the axis of the motor, and providing passagemeans communicating with and discharging into the adjacent passageopenings at the upper ends of said flues; said casing forming anunobstructed passage from the tips of the fan blades to the respectiveflues; and means under said shelves for heating the air in said space;said space providing a deep body of heated air assisting by convectionin its circulation.

4. In combination, a shell having opposite side 'walls and asubstantially horizontal intermediate wall; a centrifugal fan in theinterior of said shell near, substantially ad 'acent to and axiallyperpendicular to said intermediate wall; pressure flues on oppositesides of said interior near said opposite walls and extendingsubstantially from top to bottom and front to rear thereof and forming adeep vertical material receiving space therebetween; two vertical setsof horizontal shelves in said space leaving a vertical space alined withthe axis of the fan; said flues having a series of openings directedbetween adjacent shelves; said flues being provided with passageopenings at the end adjacent to the fan, the other ends of the fluesbeing closed; a partition extending across said interior near said fanbetween the fan'and the mid part of the interior and cooperating withsaid intermediate wall to form a fan casing having-an inlet from saidinterior at the axis of the fan, and providing passage meanscommunicating with and discharging into the adjacent passage openingsatthe adjacent ends of said flues; said casing forming an unobstructedpassage from the tips of the fan blades to the respective flues; wherebyair is evenly distributed tangentially from said tips, free of eddiesand free of lateral gravity components, whereby even distribution ismaintained; means under said shelves for heating the air in said space;said space providing a deep body of heated air assisting by convectionin its circulation.

5. An oven comprising a shell of heat insulating material having ansubstantially horizontal wall; a substantially vertical fan shaftpassing through said horizontal wall of the shell; a centrifugal fanfast on the shaft Within the shell, near said wall, and having uprightblades extending outwardly from said shaft, whereby air drawn into thefan at the middle part, is centrifugally thrown and evenly distributedsubstantially horizontally tangentially from the tips of the blades,

means forming a passage inlet to the fan whereby air is drawn into thefan substantially at the center thereof; heating means in the shell;said shaft being spaced from contact with the shell to provide an airinlet into the oven around the shaft; said horizontal wall beingprovided with an outlet opening; a stack for said outlet opening, andmeans forming an inlet passage surrounding said stack shaft and airinlet and discharging into said air inlet, thereby to extract heat fromair in said stack to pre-warm the air passing in at said air inlet.

6. An oven comprising a shell of heat insulating material forming amaterial receiving space and having a substantially horizontal wallhaving a ventilating air inlet opening, heating means in said shell; anaxially vertical fan shaft passing through said ventilating opening andspaced from contact with the shell; a centrifugal fan fast on the shaftwithin the shell, near'said horizontal :wall and opening and havingblades extending outwardly'from said shaft adapted to draw ventilatingair from said opening and to draw air from said space into the fan atthe middle part, and immediately centrifugaily force said air out?wardiy and immediately evenly mix it before it reaches said space andthen distribute it slibstantiaily horizontally tangentially from thetips of the blades, and then throughout said space,

- whereby even distribution of heat is maintained in said space andthroughout the material to be 5 heated, thereby to heat the materialevenly. V

TIMOTHY LYDON.

